Miniature auto focus voice coil actuator system

ABSTRACT

Actuator systems are provided for automatically focusing an optical image reader. Techniques are also provided which are applicable to the design of imaging engines and imaging lens systems associated with image readers of various types. More specifically, the present invention relates to lens guidance assemblies and actuator systems for automatically focusing an objective lens associated with an imaging system of an optical image reader. The optical image reader is preferably an optical code image reader for imaging optical codes, such as bar codes.

PRIORITY

[0001] This application claims priority to a U.S. ProvisionalApplication filed on Dec. 18, 2002 and assigned U.S. ProvisionalApplication Serial No. 60/434,519, the contents of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to imaging in optical reading devices,and, more particularly, to actuator systems to automatically focus atarget image in an optical reading device. Aspects of the invention areparticularly useful in solid state, area image sensor based, handheldimage readers which are positioned at variable orientations anddistances with respect to a target image.

[0004] 2. Description of the Related Art

[0005] Optical codes are patterns made up of image areas havingdifferent light reflective or light emissive properties, which aretypically assembled in accordance with a priori rules. The term“barcode” is sometimes used to describe certain kinds of optical codes.The optical properties and patterns of optical codes are selected todistinguish them in appearance from the background environments in whichthey are used. Devices for identifying or extracting data from opticalcodes are sometimes referred to as “optical code readers” of whichbarcode scanners are one type. Optical code readers are used in bothfixed and portable installations in many diverse environments such as instores for check-out services, in manufacturing locations for work flowand inventory control and in transport vehicles for tracking packagehandling. The optical code can be used as a rapid, generalized means ofdata entry, for example, by reading a target barcode from a printedlisting of many barcodes. In some uses, the optical code reader isconnected to a portable data processing device or a data collection andtransmission device. Frequently, the optical code reader includes ahandheld sensor which is manually directed at a target code.

[0006] Most conventional optical scanning systems are designed to readone-dimensional barcode symbols. The barcode is a pattern ofvariable-width rectangular bars separated by fixed or variable widthspaces. The bars and spaces have different light reflectingcharacteristics. One example of a one dimensional barcode is the UPC/EANcode used to identify, for example, product inventory. An example of atwo-dimensional or stacked barcode is the PDF417 barcode. A descriptionof PDF417 barcode and techniques for decoding it are disclosed in U.S.Pat. No. 5,635,697 to Shellhammer et al., and assigned to SymbolTechnologies, Inc., which is incorporated herein by reference. Anotherconventional optical code is known as “MaxiCode.” It consists of acentral finder pattern or bull's eye center and a grid of hexagonssurrounding the central finder. It should be noted that the aspects ofthe invention disclosed in this patent application are applicable tooptical code readers, in general, without regard to the particular typeof optical codes which they are adapted to read. The invention describedherein is also applicable to image recognition and/or analysis devices.

[0007] Most conventional scanning systems generate one or more beams oflaser light which reflects off a barcode symbol and back to the scanningsystem. The system obtains a continuous analog waveform corresponding tothe light reflected by the code along one or more scan lines of thesystem. The system then decodes the waveform to extract information fromthe barcode. A system of this general type is disclosed, for example, inU.S. Pat. No. 4,251,798, assigned to Symbol Technologies, Inc. A beamscanning system for detecting and decoding one and two dimensionalbarcodes is disclosed in U.S. Pat. No. 5,561,283, also assigned toSymbol Technologies, Inc.

[0008] Barcodes can also be read employing imaging devices. For examplean image sensor may be employed which has a two dimensional array ofcells or photo sensors which correspond to image elements or pixels in afield of view of the device. Such an image sensor may be a twodimensional or area charge coupled device (CCD) and associated circuitsfor producing electronic signals corresponding to a two-dimensionalarray of pixel information for a field of view.

[0009] Many scanners in use today employ a scanning laser beam. Somesuch systems are deployed in handheld units which may be manuallypointed at the target. Often an individual scanner is a component of amuch larger system including other scanners, computers, cabling, dataterminals, etc. Such systems are frequently designed and constructed onthe basis of mechanical and optical specifications for the scanningengine, sometimes called “form factors”. One such form factor is theSE1200 form factor employed by Symbol Technologies, Inc.

[0010] Since current form factors specify scanning engines with smallerdimensions, there is a need to provide a compact imaging engine whichcan be substituted for conventional laser line scanning engines incurrently designed and currently deployed optical code reader systems.

[0011] There is another need to provide an imaging engine which can besubstituted for form factor scanning engines in currently designed andcurrently deployed optical code reading systems to increase thereliability, versatility and target working range of such systems.

[0012] It is known in the art to use a CCD photo detector and objectivelens assembly in an optical code reader. In the past, such systems haveemployed complex objective lens assemblies originally designed for usein relatively expensive video imaging systems. Such lens assembliestypically employ multiple, large diameter, aspheric lens elements. Useof aspheric lens elements and a CCD photo detector in a code reader isillustrated in U.S. Pat. No. 5,703,349. Aspheric lens systems arerelatively costly and difficult to build. They also have a single sharpfocus and a limited depth of field, which along with conventionalaiming, illumination and signal processing and decoding algorithms,limits the versatility and working range of the system.

[0013] Symbol Technologies, Inc. has developed bi-stable high speed zonecollection systems for barcode scanners. These systems which employ lensstructures moveable into the input optical path of the scanner (drop-inoptics) are disclosed in U.S. Pat. Nos. 5,798,515 and 5,821,522.

[0014] Symbol Technologies, Inc. has also developed an easilyconstructed and inexpensive objective lens assembly for an imagingoptical code reader. This assembly is disclosed in U.S. Pat. No.6,340,114 B1, the contents of which are incorporated herein byreference. This patent also discloses an optical code reader which canbe used to read codes at a wide range of distances. Additionally, thispatent also discloses an imaging optical code reader with selectablefields of view and working depths of view appropriate to the signalprocessing and decoding capabilities of the reader.

[0015] However, notwithstanding the advancements made in the art, a needstill exists for a system which will be small enough to comply with themost recent form factor specifications while offering the same or higherdegree of versatility that may be found in existing systems.

SUMMARY OF THE INVENTION

[0016] Thus, to solve the problems in the art, the present inventionrelates to actuator systems for automatically focusing an optical imagereader. Techniques are disclosed which are applicable to the design ofimaging engines and imaging lens systems associated with image readersof various types. More specifically, the present invention relates tolens guidance assemblies and actuator systems for automatically focusingan objective lens associated with an imaging system.

[0017] It is an object of the present invention to provide a compactimaging engine which can be substituted for conventional laser linescanning engines in currently designed and currently deployed opticalcode reader systems.

[0018] It is another object of the present invention to provide animaging engine which can be substituted for form factor scanning enginesin currently designed and currently deployed optical code readingsystems to increase the reliability, versatility and target workingrange of such systems.

[0019] It is another object of the present invention to provide aneasily constructed and inexpensive moveable objective lens assembly forauto focusing an imaging optical code reader.

[0020] It is another object of the present invention to provide a lensguidance assembly for guiding a moveable objective lens assembly forauto focusing an imaging optical code reader.

[0021] It is another object of the present invention to provide severalactuator assembly embodiments for moving an objective lens assemblyalong a lens guidance assembly for auto focusing an imaging optical codereader.

[0022] It is another object of the present invention to provide animaging optical code reader having an imaging engine equipped with anobjective lens assembly capable of being moved along a lens guidanceassembly for auto focusing the imaging optical code reader.

[0023] It is another object of the present invention to provide amoveable objective lens assembly for moving along a lens guidanceassembly in accordance with a determined focus quality of the lensassembly for automatically adjusting the focus quality of an imagingoptical code reader.

[0024] Some or all of the objects previously described may be achievedin a single optical code reading engine or system. With the addition ofappropriate control circuitry and data processing software, a system maybe constructed serving the object of producing a compact, inexpensivelyfabricated imaging engine which may be substituted for existing linescan engines. The engine may be adapted for use in many differentenvironments, with various optical fields and focal distances, forreading various codes of different size. The system may also be used forimage recognition or analysis, including acquisition of data concerningthe target and its environment.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] For a better understanding of the invention, reference is made tothe following description of preferred embodiments thereof, and to theaccompanying drawings, wherein:

[0026]FIG. 1 is a simplified functional block diagram of a preferredembodiment of an imaging engine of the present invention;

[0027]FIG. 2 is a sectional view of a lens guidance assembly made inaccordance with a preferred embodiment of the present invention;

[0028]FIG. 3 is a sectional view of a lens guidance assembly made inaccordance with another preferred embodiment of the present invention;

[0029]FIG. 4 is a sectional view of an actuator assembly made inaccordance with a preferred embodiment of the present invention;

[0030]FIG. 5 is a sectional view of an actuator assembly made inaccordance with another preferred embodiment of the present invention;and

[0031]FIG. 6 is a block diagram illustrating a processing device for usein accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0032] It is to be appreciated that the present invention is applicableto any type of identification device. For illustrative purposes, adetailed description of an imaging device is provided herein. Referringnow in specific detail to the drawings in which like reference numeralsidentify similar or identical elements throughout the several views, andinitially to FIG. 1, one embodiment of an imaging engine 10 constructedin accordance with the present disclosure is shown. More specifically,FIG. 1 is a functional block diagram of a preferred embodiment of theimaging engine 10 of the present invention illustrating the arrangementof certain components of the imaging engine. The electronic hardwarecomprising the imaging subsystem and decoding subsystem is representedgenerally by a block 12, labeled “control and logic circuitry.” A doubleheaded arrow 14 illustrates the transmission of signals between an imagesensor 16 and the control and logic circuitry 12. Image sensor 16receives optical image information through an objective lens assembly18. As further illustrated in FIG. 1, an illumination source 20 andactuator assembly 22 may be controlled by signals provided by thecontrol and logic circuitry 12.

[0033] The imaging engine can be decoded (as shown in FIG. 1) orundecoded producing a raw video stream. In the undecoded case the enginecan be sold as a component to be integrated into a device that performsthe decoding.

[0034] In a preferred embodiment, the image sensor is a charge coupleddevice (CCD). However, it is to be understood that other area imagesensors may be used for the intended purpose, such as CMOS, CMD (chargemodulated device) or CID (charge injection device) sensors. Preferredembodiments of the present invention may include circuitry and/orsoftware for processing and decoding image data received from the imagesensor 16. An image sensor produces electronic signals typicallycorresponding to a two-dimensional array of pixel information for atarget image. This data is analyzed by circuitry/software based systemsto determine black and white threshold information. The pixel data isdivided into sub-images, for example, 32×32 pixel sub-images. Thesesub-images are analyzed for properties known to be associated withvarious types of optical codes and known to distinguish a particularcode from other codes and from environmental (non-code) images.

[0035] A lens assembly 18 is provided having at least one lens forfocusing light incident on the image sensor 16. The lens assembly 18 ismoveable along a lens guidance assembly 24 for changing the back focallength. The objective lens assembly 18 suitable for use in a preferredembodiment of an imaging engine of the present invention may include acylindrical shaped housing which contains at least one lens element. Thelens element may be snap fit in the cylindrical shaped housing tomaintain the lens in position on a common optical axis.

[0036] In preferred embodiments, the lens assembly 18 is automaticallymoved between a plurality of positions for automatically focusing anobject to be imaged, such as a barcode. Lens guidance assembly 24 guidesand supports the lens assembly 18 as it moves to automatically focus theobject prior to imaging the object.

[0037] Actuator assembly 22 preferably imparts either proximal or distalmotion to lens assembly 18 for moving the lens assembly either away fromthe object or towards the object, respectively. Hence, the amount ofmovement of the lens assembly 18 depends on the amount of time theactuator assembly 22 is actuated multiplied by the distance the lensassembly 18 moves over a given unit of time (velocity).

[0038] Preferably, the actuator assembly 22 is actuated afterdetermining the distance between the imaging apparatus and the object tobe imaged. A distance determining method which can be used to determinethe distance between the imaging apparatus of the present invention andthe object is disclosed in U.S. Pat. No. 6,340,114 B1 which is assignedto Symbol Technologies, Inc. The method involves using an aiming systemof the imaging optical code reader to measure the distance to a targetimage. Other distance determining methods may be used for determiningthe distance between the imaging apparatus and the object to be imagedsuch as, for example, the methods disclosed in copending U.S. patentapplication Ser. No. ______, filed ______ (Attorney docket no. 1400-4),which is incorporated by reference herein.

[0039] The determined distance to the object is then correlated by theprocessing system to a specific or approximate position of the lensguidance assembly 24 with respect to a fixed reference point (e.g., aspecific point of the lens guidance assembly, such as the centralpoint).

[0040] The processing system in communication with the imaging apparatusthen determines the amount of distance the lens assembly needs to bemoved to be at the specific or approximate position of the lens guidanceassembly with respect to the fixed, reference point. To perform thiscomputation, the processing system takes into consideration the laststored position of the reference point of the lens assembly 18 withrespect to the fixed, reference point. The last stored position of thereference point of the lens assembly 18, without taking intoconsideration the occasional need to calibrate the imaging apparatus bymanually or automatically setting the current position of the lensassembly at a known position with respect to the fixed, reference point,equates to the current position of the reference point of the lensassembly 18 with respect to the fixed, reference point.

[0041] The last “recorded” or current position is determined by theprocessing system by continuously calculating the amount of distance thereference point of the lens assembly 18 moves with respect to the fixed,reference point. For example, after an initial manufacturing setting orcalibration of the imaging apparatus, the reference point of the lensassembly 18 is located on the same plane as the fixed, reference point,or at a known distance from the fixed, reference point, e.g., thefurthermost possible position from the fixed, reference point.

[0042] Thereafter, during operation of the imaging apparatus, the lensassembly 18 is moved along the lens guidance assembly 24 to auto focusthe imaging apparatus. The distance moved by the lens assembly eitherforwards or backwards along an axis during each actuation of theactuator assembly 22 is added or subtracted, respectively, by theprocessing system to a previously recorded number. For example, if aninitial position of the lens assembly 18 is identified as position zero(preferably this initial position equates to the reference point of thelens assembly being located on the same plane as the fixed, referencepoint) and after actuating the actuation assembly for a predeterminedtime period for moving the lens assembly +0.11 mm (i.e., 0.11 mm towardsthe object to be imaged) with respect to the fixed, reference point, theprocessing system adds zero and +0.11 to determine the new position ofthe reference point of the lens assembly as being +0.11 mm from thefixed, reference point. This position is stored by the processing systemand it is the last stored position of the reference point of the lensassembly 18 or the current position of the reference point as mentionedabove. The predetermined actuation time period of the actuator assemblyis determined by the processing system according to how much the lensassembly needs to be moved to auto focus the object based on thedetermined distance between the imaging apparatus and the object.

[0043] At the current position of the lens assembly 18, the object isthen imaged by the imaging apparatus and a signal indicative of theimaged object is transmitted to an image processing system capable ofexecuting a series of programmable instructions for identifying theobject imaged and/or obtaining information encoded by the imaged object,such as information encoded by a barcode. The image processing system ispreferably integrated with the processing system.

[0044] After the imaging apparatus is auto focused and the object isimaged, the above-described auto focus imaging process is repeated for asubsequent object to be imaged. That is, upon the initiation of the autofocus imaging process by a user depressing a trigger of the imagingoptical code reader or performing some other action, the distancebetween the imaging apparatus and the object to be imaged is determinedby the aiming system in conjunction with the processing system. Theprocessing system then determines the amount of distance the lensassembly 18 is to be moved, either towards or away from the object, fromthe current position, and accordingly the actuation time period of theactuator assembly. The actuator assembly is then actuated for an amountof time equal to the actuation time period and the lens assembly 18 ismoved by an amount equal to the determined amount for auto focusing theobject to be imaged. The object is then imaged.

[0045] With continued reference to the previous example, the newposition of the reference point of the lens assembly 18 is then storedby the processing system as being +0.11 mm from the fixed, referencepoint plus the newly moved distance. If the newly moved distance is−0.73 mm (i.e., the lens assembly moved 0.73 mm away from the object tobe imaged), then the current position of the reference point of the lensassembly is determined to be −0.62 mm from the fixed, reference point.The newly moved distance is computed by determining that the referencepoint of the lens assembly 18 must be located at -0.62mm from the fixed,reference point (i.e., 0.62 mm away from the fixed, reference point inthe direction opposite from the location of the object) to maximallyauto focus the object to be imaged based on the determined distancebetween the imaging apparatus and the object.

[0046] Further still, the focus quality determination method can be usedto auto-discriminate between barcodes and other objects by analyzing thepixel data. Hence, a signal indicating the type of object and otherinformation describing the object can be provided to the imageprocessing system before a full image of the object has been captured,or, in the case where the object is constantly imaged using all of thepixels but only data representative of only a few of the pixels isanalyzed, the last captured image or accepted image is provided forimage processing.

[0047] Additionally, by knowing the type of object, the threshold focusquality range or image resolution can be adjusted “on-the-fly.” Forexample, if the object being imaged is determined to be a bar code, thethreshold focus quality can be adjusted to be within a range indicativeof low to medium image resolution. If the object being imaged isdetermined to be a fine-printed number, the threshold focus quality canbe adjusted to be within a range indicative of medium to high imageresolution. It is contemplated that a numbering system can also be usedto quantify the focus quality. For example, the range of one to ten canbe used, where the number one is equivalent to extremely poor focusquality or image resolution and the number ten is equivalent toextremely high focus quality or image resolution.

[0048] The above-described imaging apparatus may constitute part of animaging engine which also includes a power supply, decoding circuitryand video controller circuitry. In preferred embodiments, the imagingengine is less than two cubic inches in volume and is dimensioned toreplace a moving laser beam imaging engine in a handheld barcodescanner, such as SE900 and SE1200 form factor imaging engines. Such animaging engine maybe designed to read a variety of types of opticalcodes including high and low density barcodes at a working range ofbetween 1½ and 18 inches, or more.

[0049] More specifically, as shown in FIG. 1, actuator assembly 22 ispreferably configured to receive a control signal from the control andlogic circuitry 12 and cause movement of objective lens assembly 18.Movement of the objective lens assembly will change the quality of focusof an image at the image sensor 16. More specifically, in operation, thecontrol and logic circuitry 12 may direct the actuator assembly 22 tocause the objective lens assembly 18 to move between a relatively shortfocal distance and a relatively long focal distance, thereby permittingthe imaging engine to be used to read various sized images located atdifferent distances from the imaging engine, while the image remains infocus.

[0050] The illumination source 20 may consist of an illumination printedcircuit board and a lenslet plate. The illumination printed circuitboard may include a plurality of light emitting diodes. In a preferredembodiment, twenty 660 nm laser diodes are arranged on the illuminatorboard. In an alternative embodiment, laser diodes producing a higher orlower wavelength light may be employed. In either case, the laser diodesare arranged in such a way that the target area is evenly illuminated.In systems where multiple fields of view and multiple focal lengths areselectable in the imaging engine, the illumination system may providedifferent fields of illumination. Light emanating from the lightemitting diodes is projected through apertures or lenslets in a frontplate of the imaging engine.

[0051] The illumination source may produce a relatively broad beam oflower output intensity to illuminate a target barcode relatively closeto the imaging optical code reader, and a relatively narrower beam ofhigher output intensity to illuminate a target barcode relatively farfrom the reader. A portion of the illumination source for producing thelower output intensity illumination beam may comprise one or more lightemitting elements with a wide divergence pattern located relatively neara principle optical axis of the lens assembly. Additional elements maybe used to provide a longer range illumination beam of higher outputintensity. In a preferred embodiment, this function is performed bylight emitting elements with a narrow divergence pattern locatedrelatively farther from a principle optical axis of the imaging engine.These latter elements may be plural light emitting diodes eachassociated with a focusing lenslet located in a front face of theimaging engine.

[0052] In an illumination system using plural light emitting elements,certain intensity variations may occur across the illuminated field. Inpreferred embodiments of the present invention, image processingcircuits and/or software compensates signals from the image sensor forknown variations in illumination provided by the illumination source.

[0053] Optical image data is obtained and processed by circuitry andsoftware within the image sensor 16. This data may be in the form ofelectronic signals corresponding to a two-dimensional array of pixelinformation for a target image. The data may be stored for subsequentprocessing in the memory of the control and logic circuitry 12. It willbe understood that the processing software may have access to storedimage data at all levels. At various processing steps, portions of theimage data may be called up for further processing or to confirmon-going analyses.

[0054] Referring now to FIG. 2, one embodiment of a lens guidanceassembly is illustrated in cross-section in the form of a slidingbushing 32. Sliding bushing 32 is formed in a cylindrical shape having asubstantially circular cross-section. The sliding bushing 32 defines alongitudinal bore therethrough and is dimensioned to accept an objectivelens assembly 18 therein. Preferably, the dimensions of the objectivelens assembly 18 and the sliding bushing 32 are such that aninterference fit is achieved between the outer circumference of theobjective lens assembly 18 and the inner circumference of the slidingbushing 32. The interference fit will minimize the chance ofmisalignment of the lens assembly due to minor disturbing forces.Sliding bushing 32 is preferably formed of a graphite impregnated liquidcrystal material. It is also contemplated that sliding bushing 32 may beformed of Teflon or any other material having lubricious properties.Sliding bushing 32 may also be formed with flanges (not shown) on eitherend, or any other configuration, to match corresponding structure withina housing for the imaging apparatus.

[0055] Sliding bushing 32 further defines a longitudinal slot 34 in aportion thereof to facilitate at least a temporary connection with anactuator assembly which will provide the necessary forces to affectmovement of the lens assembly 18. That is, to automatically focus theoptical image, an external moving force is applied to lens assembly 18.As shown in the embodiment illustrated in FIG. 2, a moving force isapplied to lens assembly 18 in the direction indicated by arrow 36, viaa tab 38. Tab 38 attaches to lens assembly 18, and extends through slot34 in sliding bushing 32. Slot 34 has a length dimension which is longerthan the length of tab 38 to allow tab 38 and lens assembly 18 to slidewithin bushing 32 to adjust the focal point at the image sensor 16.

[0056] Arrows 40 and 42 represent the direction of the reaction forceswhich are applied to the bushing 32 as a result of the moving forceapplied to tab 38. Since the moving force applied to tab 38 creates amoment about the lens assembly 18, reactive force 40 is in the upwarddirection and reactive force 42 is in the downward direction.Notwithstanding the forces placed on the lens assembly, bushing 32 willkeep the lens assembly 18 substantially oriented along the longitudinaloptical axis.

[0057] Referring now to FIG. 3, another embodiment of a lens guidanceassembly is shown. In this embodiment of a lens guidance assembly, thelens guidance assembly is illustrated in the form of a pair of livinghinges 52. Living hinges 52 are flexible, resilient members which areconnected to a stationary frame 54 at a first end thereof and to theobjective lens assembly 18 at a second end thereof. Thus, living hinges52 provide support for the objective lens assembly 18 while maintainingthe flexibility to give objective lens assembly 18 the ability to movein response to external forces applied thereto. Living hinges 52 aresubstantially rectangular in cross-section and have notches 54 adjacentto each of the first and second ends. The flexibility of the livinghinges 52 may be varied by changing the size and/or number of notches54. The two living hinges 52 illustrated in FIG. 3 may be separate,individual units or the hinges may be connected to each other at one orboth of the first and second ends. Living hinges 52 are preferablyformed of acetal, but may be formed of other materials having similarproperties.

[0058] Tab 58 is connected to lens assembly 18 on-a-..first side of tab58 and to an actuator assembly on a second side of tab 58. As shown inthe embodiment illustrated in FIG. 3, to automatically focus an opticalimage, an external moving force is applied to lens assembly 18, via tab58, in the direction indicated by arrow 56. Arrows 60 and 62 representthe direction of the reaction forces which are applied to the livinghinges 52 as a result of the moving force applied to tab 58. Since themoving force applied to tab 58 creates a moment about the lens assembly,reactive force 62 is in the upward direction and reactive force 60 is inthe downward direction. Advantageously, living hinges 52 have lowfriction and low wear characteristics which give the user the ability tomake precise automatic focus adjustments. It is also contemplated that aforce may be applied to the lens assembly in a direction which isdifferent than the direction of arrow 56.

[0059] Referring now to FIG. 4, an imaging apparatus 70 is illustratedin accordance with a preferred embodiment of the present invention.Imaging apparatus 70 includes an image sensor 72, a lens assembly 74,and a voice coil assembly 76. Voice coil assembly 76 includes a pair ofmagnets 78 and a coil 80. As will be described in further detail below,this embodiment relies on movement of the magnets 78 to move lensassembly 74 in a direction which will achieve a desired focus of atarget image.

[0060] Lens assembly 34 is preferably supported within a lens guidesystem such as, for example, a sliding bushing or living hinges. Thelens guide system 82 illustrated in FIG. 4 corresponds to the livinghinges described above with reference to FIG. 3. Accordingly, lens guidesystem 82 provides the necessary support while remaining flexible enoughto permit movement of the lens assembly 74 to facilitate focusing of theoptical information passing therethrough.

[0061] Lens assembly 74 is configured to focus optical information onthe image sensor 72. Image sensor 72 produces electronic signalscorresponding to an array of pixel information for the target image. Asillustrated in FIG. 1, the electronic signals from image sensor 72 aretransmitted to control and logic circuitry. The control and logiccircuitry process the signals and provide an output signal to theactuator assembly relative to the focus of the target image. The methodfor determining whether the target image is in focus and what thecorresponding output signal should be is described in further detail inU.S. patent application Ser. No. 10/389,184 (attorney docket no.1400-5), which is incorporated by reference herein.

[0062] In this embodiment, the actuator assembly referred to in FIG. 1comprises a voice coil assembly 76, as illustrated in FIG. 4.Accordingly, the output signal from the control and logic circuitryvaries the flow of current through coil 80. A variation in the currentthrough coil 80 will cause a change in the flux created by coil 80 andresulting electromagnetic force between the coil 80 and magnets 78,thereby resulting in movement of the magnets 78 with respect to coil 80.For example, the variation in the current within coil 80 may cause themagnets 78 to move closer to or further away from coil 80. The magnets78 may be attached to lens assembly 74 or positioned adjacent theretosuch that movement of the magnets will cause movement of the lensassembly 74. Alternatively, lens assembly 74 may have a tab formedthereon or attached thereto, upon which the magnets apply a force tocause movement of the lens assembly.

[0063] Referring now to FIG. 5, an imaging apparatus 90 is illustratedin accordance with another embodiment of the present invention. Imagingapparatus 90 includes an image sensor 92, a lens assembly 94, and avoice coil assembly 96. The voice coil assembly 96 is comprised of ayoke 98, a magnet 100 and a coil 102. As will be described in furtherdetail below, this embodiment relies on movement of the coil_1,0,2 tomove lens assembly 94 in a direction which will achieve a desired focusof a target image.

[0064] Lens assembly 94 is preferably supported within a lens guidesystem such as, for example, a sliding bushing or living hinges. Thelens guide system 104 illustrated in FIG. 5 corresponds to the livinghinges described above with reference to FIG. 3. Accordingly, the livinghinges of lens guide system 104 provide the necessary support whileremaining flexible enough to permit movement of the lens assembly 94 tofacilitate focusing of the optical information passing therethrough.

[0065] Lens assembly 94 is configured to focus optical information onthe image sensor 92. Image sensor 92 produces electronic signalscorresponding to an array of pixel information for the target image. Asillustrated in FIG. 1, the electronic signals from image sensor 92 aretransmitted to control and logic circuitry. The control and logiccircuitry process the signals and provide an output signal to anactuator assembly relative to the focus of the target image. The methodfor determining whether the target image is in focus and what thecorresponding output signal should be is described in further detail inU.S. patent application Ser. No. 10/389,184 (attorney docket no.1400-5), which is incorporated by reference herein.

[0066] In this embodiment, the actuator assembly referred to in FIG. Icomprises a voice coil assembly, as illustrated in FIG. 5. Accordingly,the output signal from the control and logic circuitry varies the flowof current through coil 102. A variation in the current through coil 102will cause a change in the flux created by coil 102 and resultingelectromagnetic force between the coil 102 and the yoke 98. Since theyoke 98 is being held stationary by the magnet 100, the coil 102 willmove with respect to yoke 98. The coil 102 may be attached to lensassembly 94 or positioned adjacent thereto such that movement of thecoil will cause movement of the lens assembly 94.

[0067]FIG. 6 shows an example of a processing device 110 that may beused to implement, e.g., a program for determining the distances of thevarious components described above with reference to FIGS. 1-5. Thedevice 110 includes a processor 112 and a memory 114 which communicateover at least a portion of a set 115 of one or more system buses. Alsoutilizing at least a portion of the set 115 of system buses are acontrol device 116 and a network interface device 118. The device 110may represent, e.g., portions or combinations of the control and logiccircuitry 12 or any other type of processing device for use inimplementing at least a portion of the process in accordance with thepresent invention. The elements of the device 110 may correspond toconventional elements of such devices.

[0068] For example, the processor 112 may represent a microprocessor,central processing unit (CPU), digital signal processor (DSP), orapplication-specific integrated circuit (ASIC), as well as portions orcombinations of these and other processing devices. The memory 114 istypically an electronic memory, but may comprise or include other typesof storage devices, such as disk-based optical or magnetic memory. Thecontrol device 116 may be associated with the processor 112. The controldevice 116 may be further configured to transmit control signals.

[0069] The image focusing techniques described herein may be implementedin whole or in part using software stored and executed using therespective memory and processor elements of the device 110. For example,the process for determining the distances of the various components maybe implemented at least in part using one or more software programsstored in memory 114 and executed by processor 112. The particularmanner in which such software programs may be stored and executed indevice elements such as memory 114 and processor 112 is well understoodin the art and therefore not described in detail herein.

[0070] Although the illustrative embodiments of the present inventionhave been described herein with reference to the accompanying drawings,it is to be understood that the invention is not limited to thoseprecise embodiments, and that various other changes and modificationsmay be affected therein by one having ordinary skill in the art withoutdeparting from the scope or spirit of the invention. For example, theoptics may include first and second objective lenses having twodifferent fields of view. Additionally, although the illustrativeembodiments have been described with reference to an imaging device, itis to be appreciated that the term imaging device is intended toencompass any type of identification device. Thus, it is contemplatedthat the invention may be utilized in association with any type ofidentification device. Accordingly, various modifications and variationscan be made without departing from the spirit or scope of the inventionas set forth in the following claims both literally and in equivalentsrecognized in law.

1. An identification apparatus comprising: an image sensor for producingelectronic signals corresponding to optical information representativeof a target image; a lens assembly for focusing the target image on theimage sensor; and a voice coil actuator assembly configured to move thelens assembly to focus the target image on the image sensor.
 2. Theapparatus as recited in claim 1, further comprising a lens guidanceassembly, wherein the lens assembly is moved along the lens guidanceassembly to focus the target image on the image sensor.
 3. The apparatusas recited in claim 2, wherein the lens guidance assembly comprises apair of living hinges.
 4. The apparatus as recited in claim 2, whereinthe lens guidance assembly comprises a cylindrical bushing.
 5. Theapparatus as recited in claim 1, wherein the image sensor comprises acharge coupled device.
 6. The apparatus as recited in claim 1, whereinthe voice coil actuator assembly comprises a coil and a magnet adjacentto the coil.
 7. The apparatus as recited in claim 6, wherein the voicecoil actuator assembly further comprises a yoke positioned at leastpartially within a void defined by the coil.
 8. The apparatus as recitedin claim 1, wherein the optical information comprises an array of pixelinformation.
 9. The apparatus as recited in claim 8, wherein the arrayof pixel information is two-dimensional.
 10. The apparatus as recited inclaim 1, wherein the voice coil actuator assembly is positioned adjacentto the lens assembly.
 11. The apparatus as recited in claim 1, furthercomprising control and logic circuitry for processing the electronicsignals produced by the image sensor.
 12. The imaging apparatus asrecited in claim 1, wherein the voice coil actuator assembly isconfigured to automatically move the lens assembly to focus the targetimage on the image sensor.
 13. The apparatus as recited in claim 1,wherein the target image is a barcode.
 14. The apparatus as recited inclaim 1, wherein the apparatus is configured to be less than two cubicinches in volume.
 15. The apparatus as recited in claim 1, furthercomprising an illumination source for illuminating a target area. 16.The apparatus as recited in claim 15, wherein the illumination sourcecomprises a plurality of light emitting diodes.
 17. A method of readingan image with an identification apparatus, the method comprising thesteps of: producing electronic signals in an image sensor, wherein theelectronic signals correspond to optical information representative of atarget image; focusing the target image on the image sensor through alens assembly; and moving the lens assembly to focus the target image onthe image sensor via a voice coil actuator assembly.
 18. The method asrecited in claim 17, further comprising the step of determining adistance between the identification apparatus and the target image. 19.The method as recited in claim 17, further comprising the step oftransmitting the electronic signals to an image processing system whichis configured to execute a series of programmable instructions toidentify the target image.
 20. In an identification device, a lensguidance assembly for guiding and supporting a lens assembly inalignment with an optical axis comprising: a pair of living hinges, thepair of living hinges having a first end and a second end, wherein thefirst end is connected to a lens assembly and the second end isconnected to a frame of the identification device.
 21. The lens guidanceassembly as recited in claim 20, wherein each of the pair of livinghinges define a notch adjacent to the first and second ends foradjusting the flexibility of the pair of living hinges.
 22. In anidentification device, a lens guidance assembly for guiding andsupporting a lens assembly in alignment with an optical axis comprising:a cylindrical bushing, the bushing defining a hollow bore therethrough,wherein the hollow bore is dimensioned to receive a lens assemblytherein.
 23. The lens guidance assembly as recited in claim 13, whereinthe bushing defines a longitudinal slot in the circumference thereof,wherein the slot is configured to receive a tab for transferring a forcefrom an actuator to the lens assembly.
 24. A method of focusing an imagewith an identification apparatus, the method comprising the steps of:determining a distance between the identification apparatus and a targetimage; correlating the determined distance to the target image to aposition of a lens guidance assembly; determining a current position ofa lens assembly with respect to the position of the lens guidanceassembly; and determining an amount of distance that the lens assemblyneeds to be moved to focus the target image on an image sensor.
 25. Themethod as recited in claim 24, wherein the position of the lens guidanceassembly is a fixed reference position.
 26. The method as recited inclaim 25, wherein the amount of distance that the lens assembly needs tobe moved is determined with respect to the fixed reference position. 27.The method as recited in claim 24, wherein the amount of distance thatthe lens assembly needs to be moved is determined as a function of thecurrent position of the lens assembly.
 28. The method as recited inclaim 24, wherein the current position of the lens assembly iscontinuously determined.
 29. The method as recited in claim 24, whereinthe lens assembly is moved a determined distance via a voice coilactuator assembly to focus the target image on the image sensor.
 30. Anapparatus for processing information for focusing an image with anidentification apparatus, the apparatus comprising: a memory for storingat least a portion of the information; and a processor coupled to thememory and operative to determine a distance between the identificationapparatus and a target image; correlate the determined distance to thetarget image to a position of a lens guidance assembly; determine acurrent position of a lens assembly with respect to the position of thelens guidance assembly; and determine an amount of distance that thelens assembly needs to be moved to focus the target image on an imagesensor.
 31. An optical bar code reader comprising: an image sensor forproducing electronic signals corresponding to optical informationrepresentative of a target image; a lens assembly for focusing thetarget image on the image sensor; and a voice coil actuator assemblyconfigured to move the lens assembly to focus the target image on theimage sensor.